362 HlllUNDJNlD^. 



The fact that the latest broods of Martins commonly die 

 in the nest has been very often observed, but the cause of 

 it is by no means clear, notwithstanding the attention paid 

 to the subject by Mr. Blackwall (who, in his ' Zoological 

 Eesearches,' has some interesting observations upon it) and 

 others. We can hardly believe that the strong natural affec- 

 tion of the parents suddenly gives way to the instinct of self- 

 preservation, and that they voluntarily leave their oft'spring 

 to starve in the hope of saving their own life by a timely 

 retreat. Yet, if this supposition be rejected, we seem to have 

 but the alternative of thinldng that the supply of food may 

 all at once fall short in the neighbourhood of the nest, and 

 that the old birds have to seek it at such a distance that the 

 delay in taking it to their young is the cause of the latter's 

 death.* In this case there would be no desertion on the 

 part of the parents, and it could not be objected to this 

 explanation that the parents would suffer in like manner, 

 since they, finding their progeny dead from the temporary 

 want of food, would naturally depart and in an hour or two 

 be in the midst of plenty. Considering the extreme sud- 

 denness with which many kinds of insects appear and disap- 

 pear, there would seem to be no reason why the suggestion here 

 made should not be correct, and the suddenness with which 

 Martins and Swallows often vanish would also be explained.! 



About the middle of October nearly all the Martins that 

 are able to travel leave this country, but it must be under- 

 stood that the earlier broods have generally taken their depar- 

 ture some six weeks or a month sooner, since, as with 

 Swallows, these earlier broods for the most part quit their 

 birth-place and resort to localities affording greater supplies 



* Those who have reared young birds by hand, especially such as require an 

 insect diet, well know that a very short deprivation of food will often prove 

 immediately fatal. 



t Mr. A. Matthews (Zool. p. 3173) records an instance in which not only the 

 young but the parents perished, observing of the latter that "their strength 

 visibly declined," which rather confirms the view taken above, for in this case 

 supplies must have fallen off gradually. Had they suddenly ceased, the young 

 alone would probably have perished, and the old birds, having no longer a tie to 

 the si)ot, would have saved themselves. 



I 



